Multilayer ceramic substrate, method for producing same, and electronic component

Abstract

A multilayer ceramic substrate having high transverse strength, minimized warpage, and no delamination, has a laminated structure including an inner layer portion and surface layer portions, in which the thermal expansion coefficient of the surface layer portions is lower than the thermal expansion coefficient of the inner layer portion, the difference in thermal expansion coefficient between the surface layer portions and the inner layer portion is about 1.0 ppmK −1 or more, and the weight content of a component common to both a material constituting the surface layer portions and a material constituting the inner layer portion is about 75% by weight or more.

1. A multilayer ceramic substrate comprising:
 a laminated structure including at least two surface layer portions and at least one inner layer portion disposed between the at least two surface layer portions; wherein 
 a thermal expansion coefficient of the at least two surface layer portions is less than a thermal expansion coefficient of the at least one inner layer portion, a difference in the thermal expansion coefficients between the at least two surface layer portions and the at least one inner layer portion is at least about 1.0 ppmK −1 ; 
 a first material defining the at least two surface layer portions and a second material defining the at least one inner layer portion include common components; and 
 a content of the common components is at least about 75 percent by weight determined by adding a lower percent by weight value for each of the common components included in the first and second materials. 
 
     
     
       2. The multilayer ceramic substrate according to  claim 1 , wherein the difference in thermal expansion coefficient between the at least one inner layer portion and the at least two surface layer portions is about 4.3 ppmK −1  or less. 
     
     
       3. The multilayer ceramic substrate according to  claim 1 , wherein
 the first material defining the at least two surface layer portions includes glass including SiO 2  and MO, where MO represents at least one selected from CaO, MgO, SrO, and BaO, and a ratio of SiO 2  to MO is in the range of about 23:7 to about 17:13; and 
 the second material defining the at least one inner layer portion includes glass including SiO 2  and MO, and the ratio of SiO 2  to MO is in the range of about 19:11 to about 11:19. 
 
     
     
       4. The multilayer ceramic substrate according to  claim 3 , wherein
 the glass included in the first material defining the at least two surface layer portions has a SiO 2  content of about 34% to about 73% by weight; and 
 the glass included in the second material defining the at least one inner layer portion has a SiO 2  content of about 22% to about 60% by weight. 
 
     
     
       5. The multilayer ceramic substrate according to  claim 3 , wherein
 the glass included in the first material defining the at least two surface layers includes about 34% to about 73% by weight of SiO 2 , about 14% to about 41% by weight of MO, about 0% to about 30% by weight of B 2 O 3 , and about 0% to about 30% by weight of Al 2 O 3 ; and 
 the glass included in the second material defining the at least one inner layer portion includes about 22% to about 60% by weight of SiO 2 , about 22% to about 60% by weight of MO, about 0% to about 20% by weight of B 2 O 3 , and about 0% to about 30% by weight of Al 2 O 3 . 
 
     
     
       6. The multilayer ceramic substrate according to  claim 3 , wherein
 the first material defining the at least two surface layer portions includes about 30% to about 60% by weight of Al 2 O 3 ; and 
 the second material defining the at least one inner layer portion includes about 40% to about 70% by weight of Al 2 O 3 . 
 
     
     
       7. An electronic component comprising the multilayer ceramic substrate according to  claim 1 .